U.S. patent application number 15/504414 was filed with the patent office on 2017-08-17 for hearing assistance system and method.
This patent application is currently assigned to Sonova AG. The applicant listed for this patent is Sonova AG. Invention is credited to Stephan GEHRING, Daniel LUCAS-HIRTZ.
Application Number | 20170238103 15/504414 |
Document ID | / |
Family ID | 51570493 |
Filed Date | 2017-08-17 |
United States Patent
Application |
20170238103 |
Kind Code |
A1 |
GEHRING; Stephan ; et
al. |
August 17, 2017 |
HEARING ASSISTANCE SYSTEM AND METHOD
Abstract
A hearing assistance system, having first and second hearing
devices worn at respective ears of a user, each hearing device
having a BLUETOOTH.RTM. interface for wireless reception from an
external audio source device, the hearing devices being adapted to
establish a binaural data link between each other, wherein the
hearing devices are adapted to define first and second sets of
BLUETOOTH.RTM. profiles assigned to the first and second hearing
devices respectively, with the first set and the second set
differing by at least one profile, wherein the first devices are
adapted to establish a BLUETOOTH.RTM. connection to an external
device and to advertise their BLUETOOTH.RTM. profile to the
external device, wherein the hearing devices are adapted to modify,
by data exchange via the binaural link, the first and second set of
BLUETOOTH.RTM. profiles by moving at least one of the profiles from
one of the sets to the other set.
Inventors: |
GEHRING; Stephan; (Uerikon,
CH) ; LUCAS-HIRTZ; Daniel; (Rapperswil, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sonova AG |
Stafa |
|
CH |
|
|
Assignee: |
Sonova AG
Stafa
CH
|
Family ID: |
51570493 |
Appl. No.: |
15/504414 |
Filed: |
September 15, 2014 |
PCT Filed: |
September 15, 2014 |
PCT NO: |
PCT/EP2014/069593 |
371 Date: |
February 16, 2017 |
Current U.S.
Class: |
381/23.1 |
Current CPC
Class: |
H04R 25/552 20130101;
H04R 2460/03 20130101; H04R 2225/55 20130101; H04W 4/80 20180201;
H04R 25/554 20130101; H04R 25/505 20130101; H04M 1/7253
20130101 |
International
Class: |
H04R 25/00 20060101
H04R025/00; H04W 4/00 20060101 H04W004/00 |
Claims
1-23. (canceled)
24. A hearing assistance system, comprising a first hearing device
to be worn at a first one of a user's ears for hearing stimulation
of the first ear, and a second hearing device to be worn at a
second one of the user's ears for hearing stimulation of the second
ear, each hearing device comprising a BLUETOOTH.RTM. interface for
wireless reception of an external audio data stream from an
external audio source device, the hearing devices being adapted to
establish a binaural data link between the first hearing device and
the second hearing device, wherein the hearing devices are adapted
to define, by data exchange between the hearing devices via the
binaural link, a first set of BLUETOOTH.RTM. profiles assigned to
the first hearing device and a second set of BLUETOOTH.RTM.
profiles assigned to the second hearing device, with the first set
and the second set differing by at least one profile, wherein the
first hearing device is adapted to establish a BLUETOOTH.RTM.
connection to the external device and to advertise the first set of
BLUETOOTH.RTM. profiles to the external device, and wherein the
second hearing device is adapted to establish a BLUETOOTH.RTM.
connection to the external device and to advertise the second set
of BLUETOOTH.RTM. profiles to the external device, wherein the
hearing devices are adapted to modify, by data exchange via the
binaural link, the first and second set of BLUETOOTH.RTM. profiles
by moving at least one of the profiles from one of the sets to the
other set in order to obtain a modified first set of profiles and a
modified second set of profiles, once at least one of the hearing
devices finds a given mode switching criterion to be fulfilled, and
to advertise the modified first and second set of profiles to the
external device, respectively.
25. The system of claim 24, wherein each hearing device supports at
least one profile suitable for receipt of audio streaming, and
wherein the external device is adapted to select that one of the
hearing devices as a recipient for audio streaming whose set of
profiles advertised to external device includes said at least one
profile suitable for receipt of audio streaming.
26. The system of claim 24, wherein each hearing device supports at
least one profile suitable for headset use in phone calls, and
wherein the external device is adapted to select that one of the
hearing devices as a headset for phone calls whose set of profiles
advertised to external device includes the at least one profile
suitable for headset use in phone calls.
27. The system of claim 26, wherein each hearing device comprises
at least one microphone for capturing audio signals from a user's
voice and is adapted to transmit such audio signals via the
interface to the external device when selected by the external
device as a headset for phone calls.
28. The system of claim 24, wherein each hearing device is adapted
to relay audio data received from the external device to the other
hearing device via the binaural link.
29. The system of claim 28, each hearing device is adapted to relay
audio data of a stereo channel received from the external device to
the other hearing device via the binaural link (32).
30. The system of claim 24, wherein each hearing device is adapted
to advertise its assigned set of profiles to the external device
upon pairing, connecting and/or re-connecting to the external
device.
31. The system of claim 24, wherein each hearing device is adapted
to advertise a modified first and second set of profiles to the
external device only during times when there is no audio streaming
to or from the hearing devices via the interface in order to avoid
interruptions in audio streaming due to the modifications of the
first and second set of profiles.
32. The system of claim 24, wherein the mode switching criterion
includes at least one of: a parameter indicative of the quality of
the BLUETOOTH.RTM. link between the respective hearing device and
the external device; a parameter indicative of the remaining
battery capacity of the respective hearing device; the lapse of a
given time interval; occurrence of a setup of the connection to of
the respective hearing device to the external device; beginning or
end of an audio streaming to or from the respective hearing device
via the second interface; receipt of a switching message from the
external device; and booting of a hearing device.
33. The system of claim 32, wherein the given time interval is
determined by the an accumulated use time of one of the profiles by
the hearing device accumulated since the first time the profile was
used.
34. The system of claim 32, wherein the given time interval is
determined by a duty cycle defined according to expected power
consumption of the hearing devices.
35. The system of claim 32, wherein the parameter indicative of the
quality of the BLUETOOTH.RTM. link is an RSSI value, an amount of
packet errors, or a bit error rate.
36. The system of one of claim 32, wherein the mode switching
criterion in addition to the remaining battery capacity of the
respective hearing device also includes the remaining battery
capacity of the other hearing device.
37. The system of claim 32, wherein the hearing devices are adapted
to exchange status data via the binaural link prior to deciding
that the mode switching criterion is fulfilled.
38. The system of claim 37, wherein the hearing devices are adapted
to periodically exchange status data via the binaural link.
39. The system of claim 24, wherein the hearing devices are adapted
to record parameters relating to modifications of the sets of
profiles.
40. The system of claim 24, wherein, when the sets of profiles are
modified, at least a least power consuming profile remains in the
set, while at least one of more power consuming profiles is moved
to the other set.
41. The system of claim 24, wherein each hearing device is adapted
to take over all profiles of the other set into its own set in case
it finds that the other hearing device lost its connection to the
external device and/or its connection via the binaural link and to
redistribute the profiles onto the sets once it finds that the
other hearing device has restored its lost connection.
42. The system of claim 41, wherein each hearing device is adapted
to mix down a stereo audio stream received from the external device
in case it finds that the hearing device lost its connection via
the binaural link to the other hearing device.
43. The system of claim 24, wherein the binaural link is a
wireless, inductive, link.
44. The system of claim 24, wherein the hearing devices are
electro-acoustic hearing aids or auditory prosthesis devices.
45. The system of claim 24, wherein the external device is one of a
phone device, a personal computer, a tablet computer, a radio
device, a music or media player, a TV set, a wireless microphone or
a generic remote control.
46. A method of providing hearing assistance to a user wearing a
first hearing device at a first one of the user's ears and a second
hearing device at a second one of the user's ears, each hearing
device being adapted to establish a binaural data link between the
first hearing device and the second hearing device and comprising a
BLUETOOTH.RTM. interface for wireless reception of an external
audio data stream from an external audio source device, the method
comprising: defining, by data exchange between the hearing devices
via the binaural link, a first set of BLUETOOTH.RTM. profiles
assigned to the first hearing device and a second set of
BLUETOOTH.RTM. profiles assigned to the second hearing device, with
the first set and the second set differing by at least one profile,
establishing a BLUETOOTH.RTM. connection between the first hearing
device and the external device, with the first hearing device
advertising the first set of BLUETOOTH.RTM. profiles to the
external device, and a BLUETOOTH.RTM. connection between the second
hearing device and the external device, with the second hearing
device advertising the second set of Bluetooth profiles to the
external device, modifying, by data exchange between the hearing
devices via the binaural link, the first and second set of
BLUETOOTH.RTM. profiles by moving at least one of the profiles from
one of the sets to the other set in order to obtain a modified
first set of profiles and a modified second set of profiles, once
at least one of the hearing devices finds a given mode switching
criterion to be fulfilled, and advertising the modified first and
second set to the external device.
Description
BACKGROUND OF THE INVENTION
[0001] Field of the Invention
[0002] The invention relates to a hearing assistance system,
comprising a first hearing device to be worn at a first one of a
user's ears, and a second hearing device to be worn at a second one
of the user's ears, with each hearing device being adapted to
establish a binaural data link between the first hearing device and
the second hearing device and comprising a BLUETOOTH.RTM. ("BT")
interface for wireless reception of an external audio data stream
from an external device, such as a phone device.
[0003] Description of Related Art
[0004] When transporting audio, BLUETOOTH.RTM. Classic profiles,
such as the Advanced Audio Distribution Profile (A2DP) or the Hands
Free Profile (HFP), offer a point-to-point link from an audio
source to an audio destination.
[0005] Typically, the interface for binaural communication, which
may use an inductive link, is a short range interface having lower
power consumption than the BLUETOOTH.RTM. interface.
[0006] Since power consumption is an issue for ear level devices,
binaural hearing assistance systems have been developed, wherein
the external audio stream is received only by one of the hearing
devices via the long range interface and is forwarded to the other
device via the binaural short range interface.
[0007] U.S. Pat. No. 8,300,864 B2 relates to a binaural hearing aid
system, wherein an audio stream from a telephone device is
transmitted via a short range inductive link to one of the hearing
aids and is forwarded via a second wireless link which is used by
the hearing aids to exchange data to the other hearing aid.
[0008] U.S. Pat. No. 8,041,066 B2 relates to a binaural hearing aid
system, wherein one of the two stereo channels received by one of
the hearing aids via a wireless link is forwarded to the other
hearing aid via a wireless link.
[0009] Other examples wherein an audio stream received via a BT
link from an audio source is relayed to the other ear are described
in U.S. Pat. No. 8,706,038 B2, U.S. Pat. No. 9,002,044 B2 and U.S.
Pat. No. 8,155,335 B2, wherein the binaural link likewise may be a
BT link (U.S. Pat. No. 8,706,038 B2 and U.S. Pat. No. 9,002,044 B2)
or may be an NCF link (U.S. Pat. No. 8,155,335 B2)
[0010] U.S. Patent Application Publication 2009/0197532 A1 relates
to a pair of earphones, wherein in a first mode one of the earphone
receives an audio stream via a BT link from a mobile phone and
relays it via a different wireless link to the other earphone, and
wherein in a second mode the roles of the earphones are
interchanged; switching between the two modes occurs according to
the battery levels of the earphones in order to achieve balanced
battery drain.
[0011] U.S. Patent Application Publication US 2011/0158441 A1
relates to similar system comprising a pair of BT earphones,
wherein the wireless link connecting the earphones is a BT link
like the BT link via which the audio stream from the mobile phone
is received; the roles of the earphones are switched according to
the respective battery levels.
[0012] U.S. Pat. No. 8,526,648 B2 relates to a binaural hearing
assistance system, wherein an audio signal from a wireless
microphone is transmitted to the hearing devices, wherein the link
quality to each hearing device is monitored, and wherein the signal
received via the better link is relayed via a binaural link to the
other hearing device.
[0013] International Patent Application Publication WO 2010/008861
A2 relates to a network system, wherein information concerning the
BT protocols/services available for a device of the system is
communicated to other devices in the network via another network
link, such as WiFi.
[0014] U.S. Patent Application Publication US 2010/0167652 A1
relates to a system comprising a mobile phone and a BT headset,
where there is an internal protocol switching in the mobile phone
depending on the use situation.
[0015] According to U.S. Pat. No. 8,150,323 B2, the BT connection
from a mobile phone to a headset may be changed according to the
presence of a phone call from a simplex to a duplex mode when music
is played.
[0016] U.S. Pat. No. 8,050,439 B2 relates to a binaural hearing
system, wherein a bidirectional wireless link between the two
hearing aids as used to exchange information concerning the battery
charge status of each hearing aid in order to reduce power
consumption of the hearing aid having the lower remaining battery
lifetime once the difference of the remaining battery charges
exceeds a certain limit.
[0017] U.S. Pat. No. 8,712,083 B2 relates to data logging in a
wireless hearing aid system in order to modify link parameters in a
manner to enhance reliability and link quality.
SUMMARY OF THE INVENTION
[0018] It is an object of the invention to provide for a binaural
hearing assistance system which is able to receive an external
audio stream in a robust manner via a standard BT link from an
external device, such as a mobile phone, wherein the battery
lifetime and device lifetime may be maximized. It is a further
object to provide for a corresponding hearing assistance
method.
[0019] According to the invention, these objects are achieved by a
hearing assistance system and a hearing assistance method as
described herein.
[0020] The invention is beneficial in that, by modifying the set of
BT profiles advertised by each hearing device to the external
device in a synchronized manner according to the fulfillment of
given mode switching criteria, the hearing devices may switch their
roles taken with regard to the communication with the external
device in flexible manner in response to various usage scenarios,
while both hearing devices may stay connected with the external
device. Keeping both hearing devices connected to the external
device enables particularly rapid role switching and ensures that
the external device may inform the user that both hearing devices
stay connected to the external device, thereby avoiding confusion
of the user. The role switching may serve to balance power
consumption and wear of the hearing devices and to maintain
connectivity, by relaying of audio streams to the other ear, for
example in case of a weak BT link to one of the hearing
devices.
[0021] The BT link preferably uses BT Classic.
[0022] Hereinafter, examples of the invention will be described
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a schematic representation of an example of a
hearing assistance system according to the invention;
[0024] FIG. 2 is a block diagram of an example of a hearing device
to be used in a hearing assistance system according to the
invention;
[0025] FIG. 3 is a message sequence chart of an example of a
pairing process of a hearing assistance system according to the
invention;
[0026] FIG. 4 is a message sequence chart of an example of a
process for setting up a connection in a hearing assistance system
according to the invention;
[0027] FIG. 5 is a message sequence chart of two examples of an
audio streaming process in a hearing assistance system according to
the invention;
[0028] FIG. 6 is a message sequence chart of an example of a role
switching process in a hearing assistance system according to the
invention; and
[0029] FIG. 7 is a message sequence chart of another example of a
role switching process in a hearing assistance system according to
the invention;
DETAILED DESCRIPTION OF THE INVENTION
[0030] FIG. 1 is a schematic representation of an example of a
hearing assistance system according to the invention, comprising a
first hearing device 10 to be worn at one ear of a user, a second
hearing device 11 to be worn at the other ear of the user and an
external device 12, wherein the first and second hearing devices
10, 11 may communicate with each other via a binaural link 32 and
with the external device 12 via a respective BLUETOOTH.RTM. link
30, 31.
[0031] FIG. 2 shows a block diagram of an example of a hearing
device 10 forming part of a hearing assistance system according to
the invention shown in FIG. 1, wherein one such device 10 is to be
worn at a first one of a user's ears for stimulating the first ear
and a second such device is to be worn at the other of the user's
ears for stimulating the other ear (the two devices are designated
by 10 and 11 in FIG. 1).
[0032] Preferably, the hearing device 10 is a hearing instrument,
such as a BTE (behind the ear), ITE (in the ear) or CIC (completely
in the channel) hearing aid. However, the hearing devices, for
example, also could be an auditory prosthesis, such as a cochlear
implant device. According to another example, the hearing devices
could form a headset or headphones for a normal hearing person.
[0033] According to the example of FIG. 2, the hearing device 10 is
an electro-acoustic hearing aid comprising a microphone arrangement
13 for capturing audio signals from ambient sound, an audio signal
processing unit 14 for processing the captured audio signals and an
electro-acoustic output transducer (loudspeaker) 16 for stimulation
the user's hearing according to the processed audio signals.
[0034] The hearing instrument 10 also comprises a first wireless
interface 18 and a second wireless interface 20. Typically, the
first interface 18 is designed for a shorter range and a lower
power consumption than the second interface 20; accordingly. The
first interface 18 comprises an antenna 22 and a transceiver 24,
and the second interface comprises an antenna 26 and a transceiver
28.
[0035] The first interface 18 is provided for enabling wireless
data exchange between the first hearing instrument 10 and the
second hearing instrument 11 via a wireless link 32 which
preferably is an inductive link which may operate, for example, in
a frequency range of 6.765 MHz to 13.567 MHz, such as at 10.6 MHz.
However, rather than being implemented as an inductive link, the
wireless link 30 in principle also could be far-field link
typically requiring a lower power consumption than the link of the
second interface 20, such as a power optimized proprietary
digitally modulated link operating in the 2.4 GHz ISM band.
According to further, less preferred alternative the binaural link
32 even may be a wired link, such as a CROS (Contralateral Routing
of Signal) link.
[0036] In particular, the first interface 18 may be designed to
form part of a hearing instrument body area network (HIBAN). In
particular, the hearing instruments 10, 11 may exchange audio data
and/or parameter settings/commands required for binaural operation
of the two hearing instruments 10, 11, for example, in a
master-slave configuration.
[0037] The second interface 20 is provided for exchanging data via
a Bluetooth link 30, 31 with the external device 12.
[0038] In the case that the binaural link 32 is a wireless link,
the protocol/interface for the binaural link 32 and the BT links
30, 31 may be the same (in this case the interface 20 used for the
binaural link 32 also could be used for data reception from the
external device 12 via the links 30, 31) or it may be different
(requiring two separate interfaces 18, 20 for the links 32 and
30/31, respectively).
[0039] Preferably, the external data stream is an audio data stream
which may be mono stream or a stereo stream. The external device 12
typically is a phone device, such as a mobile phone, a DECT phone
device or an internet phone device ("Voice over IP").
Alternatively, it may be other type of electronic
media/communication device, such as a personal computer, a tablet
computer, a radio device, a music/media player, a HiFi set, a TV
set, a wireless microphone or a generic remote control. According
to a further alternative, it may be a public address/announcement
system (like in an airport or a place of worship).
[0040] The hearing instrument 10 also may comprise a controller 38
for controlling operation of the hearing instrument 10, with the
controller 38 acting on the signal processing unit 14, the
transceivers 24 and 28.
[0041] The hearing instrument 10 also may comprise a unit 40 for
determining the charging status of the battery 42 of the hearing
instrument 10, which provides a corresponding battery charge status
signal to the controller 38.
[0042] In FIG. 3, a message sequence chart of an example of a
pairing process of the system of FIG. 1 is shown, wherein the user
first may initiate pairing between the first hearing device 10 and
the external device 12 (step A1), whereupon the external device 12
and the first device 10 pair, with the first device 10 informing
the external device 12 with regard to the BT profiles supported by
the first device 10 (step A2).
[0043] In the example illustrated in FIGS. 1 to 7, it is assumed
that both devices 10, 11 support the "Advanced Audio Distribution
Profile" (A2DP) which is suitable for audio streaming from one BT
device to another BT device (in the present example, it may be used
for streaming of a mono or stereo audio stream, such as music, from
the external device 12 to the hearing devices 10, 11), and the
"hands-free profile" (HFP) which is suitable for using a headset in
phone calls (in the present example, the external device 12 is a
phone device which may use the devices 10, 11 as a phone headset).
Both profiles offer a point-to-point link from an audio source to
an audio destination.
[0044] After pairing of the external device 12 with the first
device 10, the user may initiate pairing of the external device 12
with the second device 11 (step A3), whereupon the external device
12 and the second device 12 pair, with the second device informing
the external device 12 that it supports the A2DP and HFP profiles
(step A4).
[0045] Before or after pairing with the external device 12, the
first and second devices 10, 11 define, by data exchange via the
binaural link 32, a first set of BT profiles assigned to the first
device 10 and a second set of BT profiles assigned to the second
device 11, wherein the first set and second set are different in
that they differ by at least one profile. When establishing a
connection between the respective hearing device 10, 11 and the
external device 12, the hearing device advertises the BT profiles
presently assigned to it to the external device 12, with the
external device 12 then selecting the respective hearing device 10,
11 for a certain role/task in conformity with the advertised
profiles. Thus, the roles taken by the hearing assistance devices
10, 11 may be changed/switched by modifying the respective set of
BT profiles assigned to the respective hearing device 10, 11 (and
subsequently advertising the modified set of profiles to the
external device 12)--typically in response to the changes in the
use conditions of the system--, while both devices 10, 11 may stay
connected to the external device 12, as will be illustrated in more
detail below.
[0046] Thus, "advertising a set of BT profiles" is to be understood
such that it relates to a process wherein one of the hearing
devices communicates to the external device 12 via the respective
BT link that from now on the hearing device supports exclusively
the BT profiles listed in the advertised set of profiles; according
to the present invention, the purpose of advertising a modified set
of profiles differing by at least one profile from the previously
advertised set of profiles is to trigger/initiate a change of the
role taken by the hearing device with regard to the external device
12. The external device, after having received the advertising
message may carry out the role change immediately or with same
delay.
[0047] It is also to be understood that a "set of BT profiles"
generally may include any number of profiles; in particular, the
set may include no profile at all, i.e., the set may be empty.
[0048] While FIG. 3 is a high level overview of the pairing
process, it is to be understood that the pairing process may
include other features; for example, the pairing process can be
synchronized between the two devices 10, 11 in order to ensure that
there is at least a certain time period between the individual
pairing process of each device 10, 11; in such case, the device 10,
11 which is paired first, may notify the other device of the
successful pairing, and the other device then may wait for a
certain time interval before it activates its own pairing
process.
[0049] FIG. 4 is a message sequence chart of an example of a
process for setting up a connection between each device 10, 11 and
the external device 12, wherein the first and second device 10, 11
define a first set of BT devices assigned to the first device 10
and a second set of BT profiles assigned to the second device 11;
in the example, the first set consists of the A2DP profile, and the
second set consists of the HFP profile, with the definition of the
set of profiles being achieved by a corresponding message sent from
the first device 10 via the binaural link 32 to the second device
11 (see step B1).
[0050] Thereafter, the first device 10 sends a message via the BT
link 30 to the external device 12 which advertises the A2DP profile
to the external device 12 for being used in the connection (Step
B2), and the second device 11 sends a corresponding message via the
BT link 31 to the external device 12 advertising the HFP profile to
the external device 12 for being used in the connection (step B3),
with the external device 12 registering the respective profiles for
use with the respective hearing device10 and 11, respectively.
[0051] Based on such profile setting, the external device 12 will
use the first device 10 as the recipient for audio streaming (such
as stereo music streaming), whereas it will use the second device
11 as a headset for phone calls.
[0052] FIG. 5 is a message sequence chart of corresponding audio
signal exchange processes, with the upper part of FIG. 5 showing a
message sequence chart during a phone call, and with the lower part
of FIG. 5 showing a message sequence chart during music
streaming.
[0053] According to the first (upper) example of FIG. 5, the
external device 12 recognizes an incoming phone call and looks for
a device having advertised availability of the HFP profile to the
external device 12 before, with the external device 12 accordingly
selecting the second device 11 for being used as a headset for the
present phone call (step C1). The external device 12 then sets up
an audio exchange connection with the second device 11 using the
HFP profile (step C2). After having set up the connection, the
external device 12 transmits the received remote voice signal to
the second device 11, which generates corresponding sound at the
respective ear and in addition relays the received audio stream via
the binaural link 32 to the first device 10 which generates
corresponding sound at the other ear. When the user of the devices
10, 11 speaks, the microphone arrangement 20 of the second device
11 may capture the user's voice and may transmit a corresponding
audio stream via the BT link 31 to the external device 12 (step
C3); alternatively, it would be possible to capture the user's
voice by the microphone arrangement 20 of the first device 10 and
to route the that microphone input of device 10 via the binaural
link to device 11 and from there to device 12, but, since that
variant would incur a higher delay, it is less preferred. Thereby,
binaural playback of a mono audio signal corresponding to remote
voice is realized. At the end of the phone call, the audio
connection using the HFP profile is torn down (step C4).
[0054] In the second (lower) example of FIG. 5, the external device
12, upon a request to play music, looks for a device having
advertised support of the A2DP profile before and accordingly
selects the first device 10 (step D1). Thereafter, the external
device 12 sets up an audio streaming connection to the first device
10 using the A2DP profile (step D2) and streams a stereo audio
signal via the BT link 30 to the first device 10 which generates
sound corresponding to one of the two channels and relays the other
channel via the binaural links 32 to the second device 11 which
generates sound corresponding to the other channel at the other ear
(step D3). At the end of the music playing action, the audio
streaming connection is torn down by the external device 12 (step
D4).
[0055] FIG. 6 shows a message sequence chart of an example of a
role switching process. The upper part of FIG. 6 includes a
repetition of steps B2 and B3 of FIG. 4 (first device 10
advertising A2DP profile, second device 11 advertising HFP
profile), and of steps D1 to D4 of FIG. 5 (playing music via the
first device 10). In step E1 the first device 10 recognizes that a
certain mode switching criterion is fulfilled, namely that the
remaining battery capacity has decreased below a certain threshold
(as indicated by the unit 40), whereupon the first device 10
decides to initiate a mode switching in order to balance battery
drain with the second device 11. To this end, the first device 10
sends via the BT link 30 a message to the external device 12 for
tearing down the A2DP connection, whereupon the external device 12
changes the registration of the first device 10 accordingly (step
E2); further, the first device 10 sends, via the binaural links 32,
a message to the second device 11 to modify the profile sets
accordingly, i.e. the A2DP profile is moved from the first set of
profiles assigned to the first device 10 to the second set of
profiles assigned to the second device 11, so that the first set
after this modification no longer includes any profile, whereas the
second set of profiles now includes both the HFP profile and the
A2DP profile (step E3).
[0056] The expression "moving a profile from one set to another
set" is to be understood such that, when modifying the first and
second set of profiles, a certain profile, such as the HFP, which
was exclusively included in one of the sets, e.g., in the first set
but not in the second set, prior to the modification will be
included, after the modification, exclusively in the other set,
e.g., in the second set but no longer in the first set. In
particular, such "moving of a profile" relates to changing of
entries/items on lists (i.e., the sets), but does not include any
physical movement of the profile as such.
[0057] Thereafter, the second device 11 sends a message to the
external device 12 to tear down the AFP connection (step E4) in
order to enable a "re-start" of the connection based on the
modified sets of profiles. In the example of FIG. 6, the second
device 11 now takes over all profiles and sends a corresponding
message to the external device 12 in order to set up a connection
based both on the A2DP and AFP profile, which is registered
accordingly by the external device 12 (step E5).
[0058] When now the external device 12 is requested to play music,
it will select the second device 11, rather than the first device
10, as the audio stream recipient in order to set up a
corresponding audio stream, with the second device 11 now relaying
the respective audio channel via the binaural link 32 to the first
device 10 (step E6).
[0059] FIG. 7 shows a message sequence chart of another example of
a role switching between the first and second device 10, 11. In the
example of FIG. 7, the first device 10 "disappears" in the sense
that the second device 11 no longer receives messages from the
first device 10 (e.g., because the battery of the first device 10
has run out), in particular messages concerning the distribution of
the roles of the two devices 10, 11 (step F1); also the external
device 12 no longer receives messages from the first device 10.
Such "loss" of the first device 10 is registered by both the
external device 12 and the second device 11 (step F2). As a
consequence, the second device 11 sends a message to the external
device 12 in order to tear down the existing HFP connection (step
F3), with the second device 11 now taking over all profiles
advertised by the first device 10 and establishing a corresponding
new connection with the external device 12 based on both the A2DP
profile and the HFP profile (step F4).
[0060] When the external device 12 now is requested to play music,
it will select the second device 11, rather than the first device
10, as an audio stream recipient and will send a stereo audio
stream to the second device 11 (step F5); in this regard it is to
be noted that, since the first device 10 presently is not in the
range of the binaural link 32, no relaying of the respective audio
channel to the first device 10 will take place. In such case the
second device 11 may down-mix the received stereo audio signal to a
mono signal.
[0061] Preferably, a mode/role switching process (which is
initiated by corresponding advertising of modified sets of profiles
to the extended device 12) takes place only during times when there
is no audio streaming to or from the hearing assistance devices via
the BT link 30, 31, thereby avoiding interruptions of the sound
generated from the streamed audio signals. However, in some cases
it might be not desirable to wait until the present audio streaming
phase is terminated, for example if the device acting as the audio
stream recipient is "lost". In such cases a mode switchover may
happen during audio streaming. In order to avoid an interruption of
the sound created from the audio stream, the audio stream receiving
device may buffer the received audio data sufficiently (at the
penalty of introducing a larger audio latency) so that during the
time interval required to trigger the other device to take over the
audio streaming link and to establish the link by the other device
the buffered data is sufficient to continue the sound
generation.
[0062] The expression "mode switching criterion" is to be
understood as designating a certain event which has to be found to
take place (or a condition which has to be found to be fulfilled),
such as a certain parameter reaching a certain limit/threshold, so
that a certain role/task attributed to one of the hearing devices
should be changed, e.g., transferred to the other hearing device.
That is, the fulfillment of a "mode switching criterion" will
trigger some kind of mode switching of the respective hearing
device.
[0063] The mode switching criterion, i.e., the event triggering a
mode switching action, may include a plurality of
parameters/events: one of the parameters may be a parameter
indicative of the quality of the BT link 30, 31 between the
respective hearing device 10, 11 and the external device 12; for
example, such link quality parameter may be an RSSI value, an
amount of packet errors or a bit error rate, with the mode
switching being initiated once the respective link quality
parameter falls below a given threshold.
[0064] According to another example, the parameters may include a
parameter indicative of the remaining battery capacity of the
respective device, for example the present battery voltage, wherein
mode switching is initiated once the remaining battery capacity
falls below a given threshold value. In this regard, the devices
10, 11 may take into account not only the remaining battery
capacity of one of the devices 10, 11, but the remaining battery
capacity of both devices 10, 11 in order to take a joint decision
regarding the role switching; however, according to an alternative,
one of the devices 10, 11 may unilaterally declare that the roles
should be switched because its power is too low.
[0065] In case of low power, the respective device 10, 11 may first
only turn off the BT link 30, 31 (with the other device taking over
the respective protocols), while still maintaining the binaural
link to the other device 11, 10 in order to be able to receive a
relayed audio stream and/or control traffic (this is appropriate in
case that the binaural link 32 consumes less power than the BT link
30, 31); once the remaining power reaches a second threshold lower
than the first power threshold, the respective device 10, 11 may
declare that it is now going offline and will not even support the
binaural link 30.
[0066] In the case that one of the devices 10, 11 went offline with
regard to its BT link 30, 31, the external device 12 may notify,
for example visually, the user accordingly, or it may notify via
the BT link the other device that there is a connectivity problem,
so that the other device may take over the profiles and relay the
received audio data via the binaural link 32 to the device having
the connectivity problems.
[0067] Instead of dynamically determining the remaining power of
the devices 10, 11 via the unit 40, an appropriate duty cycle may
be determined according to the expected power consumption of the
devices 10, 11, with the mode switching then occurring according to
such duty cycle, i.e., the mode is switched once a respective time
interval determined by the duty cycle lapses. Such duty cycle may
take into account, for example, that one of the devices 10, 11 has
a significantly higher basic power consumption than the other due
to an asymmetric hearing loss of the user, in which case the other
device 11, 10 has to take more of the BT communication tasks (such
as the audio streaming).
[0068] According to another approach, the total use time of each of
the profiles in each of the devices 10, 11 may be recorded and may
be used to determine the times when a mode switching should occur;
in such case, mode switching would be triggered by the lapse of a
certain time interval determined by the recorded total profile use
times.
[0069] According to a more simple approach the devices 10, 11 may
unconditionally switch the advertised profiles after or before each
connection setup; alternatively, mode switching may be triggered by
setup or tear down of an audio streaming process.
[0070] As already mentioned above, according to a further
alternative approach, mode switching may be triggered by receipt of
a respective switching message from the external device 12. In
general, the decision to change the mode may be taken by one of the
devices 10, 11 alone, or the devices 10, 11 may exchange status
data via the binaural link 32 prior to deciding on mode switching
(i.e. prior to deciding that a mode switching criterion is
fulfilled); in particular, the devices 10, 11, may periodically
exchange such status data via the binaural link 32.
[0071] Such periodic exchange of status data may be used as
"keep-alive" messages in order to detect whether the other device
is still in range of the binaural link 32.
[0072] According to one example, the devices 10, 11 may record
parameters relating to the mode switching/modifications of the sets
of profiles; for example, the devices 10, 11 may record the time
when the last advertising of the sets of parameters to the external
device occurred (e.g., the time of the last switchover may be
persistently recorded).
[0073] Preferably, when one of the devices 10, 11 which has been
"lost", later on "re-appears", the devices 10, 11 may
re-synchronize and redistribute the profiles according to the
distribution before the "loss".
[0074] According to one example, in case of a role switching
triggered by low power of one of the devices 10, 11, at least the
least power consuming profile may remain in the set assigned to the
device having the low power state, while at least one of the more
power consuming profiles, in particular the most power consuming
profile, is moved to the profile set assigned to the other
device.
* * * * *